1. Field of the Invention
The present invention relates generally to integrated circuit design of a timing source adapted to generate a very accurate time reference over a significant time period, and, in particular, such a source usually operates continuously and is adapted to provide accurate low power operation.
2. Description of the Related Art
In general, in the descriptions that follow, I will italicize the first occurrence of each special term of art that should be familiar to those skilled in the art of integrated circuits and systems. In addition, when I first introduce a term that I believe to be new or that I will use in a context that I believe to be new, I will bold the term and provide the definition that I intend to apply to that term. In addition, throughout this description, I will sometimes use the terms assert and negate when referring to the rendering of a signal, signal flag, status bit, or similar apparatus into its logically true or logically false state, respectively, and the term toggle to indicate the logical inversion of a signal from one logical state to the other. Alternatively, I may refer to the mutually exclusive boolean states as logic—0 and logic—1. Of course, as is well known, consistent system operation can be obtained by reversing the logic sense of all such signals, such that signals described herein as logically true become logically false and vice versa. Furthermore, it is of no relevance in such systems which specific voltage levels are selected to represent each of the logic states.
Many systems require a timing source adapted to generate a very accurate time reference over a significant time period. Because such sources usually operate continuously, accurate low power operation is highly desirable. Generally, the high power consumption of current integrated circuit technology has become a critical problem for mobile electronics that must run for days, months, or even years on a single battery charge. As is known, an accurate clock generator is a key element in the overall design of integrated circuits. Such a clock generator may be used in an integrated circuit to dramatically reduce power consumption, significantly extend battery life, and reduce battery size and cost.
Since various factors often result in higher variability in the frequency of the timing source, systems may implement a mechanism for calibrating the generated clock to a known reference frequency using any of a number of known analog or digital techniques. As noted in my Parent Provisional, one such technique used in prior art systems is known as burst pulse modification.
As discussed in my Parent Provisional, I submit that what is needed is an improved method and apparatus for generating an accurate clock generator timing source, comprising minimal jitter, excellent resolution, and an extended calibration range, for use, for example, in a system requiring accurate low power operation. In particular, I submit that such a method and apparatus should provide performance generally comparable to the best prior art techniques while requiring less circuitry and consuming less power than known implementations of such prior art techniques.